Most of the semiconductor manufacturing apparatuses are provided with a wafer chuck for holding thereon a wafer. Further, various processes are performed while the wafer is being held on the wafer chuck.
As shown in FIGS. 2A and 2B, a wafer chuck includes a mounting table 1 for mounting thereon a wafer W and capable of rotating in forward and backward directions; a plurality of (e.g., three) pins which protrude and retreat with respect to a mounting surface 1A of the mounting table 1; a substantially ring-shaped joint 3 for connecting the pins 2; cam followers 4A protruded radially outwards from a plurality of locations of the joint 3; cams 4B positioned under the cam followers 4A to be engaged therewith; and first biasing mechanisms 5 for constantly biasing the pins 2 downward. Each of the first biasing mechanisms 5 has a coil spring 5A and an axis 5B elongated downwards from a bottom surface of the mounting table to pass through the coil spring 5A.
As the mounting table 1 rotates in forward and backward directions, the cam followers 4A rotate along the cams 4B. Accordingly, the pins 2, in cooperation with the first biasing mechanisms 5, move (up and down) in an axial direction via through holes 1B formed in the mounting table 1, enabling the wafer W to be delivered and received above the mounting table 1.
Such wafer chuck can be used under the vacuum environment or the atmospheric pressure environment.
Among wafer chucks, there is the one delivering and receiving a diced wafer W by using a dicing frame DF, as shown in FIG. 3.
The dicing frame DF is used for dicing the wafer W into multiple chips T. As partially enlarged in FIG. 4B, the diced wafer W is completely separated as the chips T and supported by the dicing frame DF via a film F having thereon notched grooves.
In the wafer chuck of FIG. 3 for use in, e.g., a probe apparatus, for testing the wafer W, a plurality of rods 6A of cylinder mechanisms 6 are raised to a position indicated by a dashed dotted line and, then, the diced wafer W accommodated on the dicing frame DF is received from a transfer mechanism of the probe apparatus by a plurality of receiving parts 6B provided at leading ends of the rods 6A. Further, while the receiving parts 6B are returning to fixed blocks 6C provided below the mounting table 1A, the dicing frame DF and the wafer W are mounted on the mounting table 1A, as indicated by a dashed dotted line of FIG. 3. After the receiving parts 6B reach supports 6D protruded from the fixed blocks 6C, frame parts of the dicing frame DF which tend to fall by gravity are adsorptively held by the supports 6D. In such a state, an electrical characteristic test is performed on each of the chips T of the wafer W mounted on the mounting table 1A.
However, when the diced wafer is mounted by using a dicing frame DF on the mounting table 1 of the wafer chuck of FIGS. 2A and 2B used for an undiced wafer, the pins 2 are lowered from a position indicated by a dashed dotted line of FIG. 4A to a position indicated by a solid line of FIG. 4A and then retreated into the through holes 1B of the mounting table 1, as illustrated in FIGS. 4A and 4B. At this time, gaps are formed between leading ends of the pins 2 and the film F supporting the wafer W, thereby generating recess portions on the mounting table 1. Due to the presence of the recess portions, the chips T positioned on the through holes 1B may be damaged when a stylus pressure of a probe for the electrical characteristic test is applied to the corresponding chips T. Moreover, in case each of the chips T is scaled-down along with a trend toward a high integration of a wiring structure or the like, an area of a chip T may be smaller than that of a through hole 1B, as illustrated in FIG. 4B. In that case, it is not possible to apply the stylus pressure of the probe required for the test on the chips T disposed on the through holes 1B, so that the electrical characteristic test may not be carried out.